In indoor units of separate type air conditioning devices which include an indoor unit and an outdoor unit, most indoor units which are hung on the upper part of the wall surface of the room to be air conditioned include an air inlet for the room air formed on the top of the housing of the indoor unit. The indoor units further include a heat exchanger and an air sending fan in the housing, and the room air which is introduced from the air inlet on the top into the housing by rotating an air sending fan is cooled or heated by the heat exchanger so as to provide conditioned air from an air outlet disposed in a lower part on the front side of the housing.
An air outlet passage wall is disposed on the back side of the air sending fan so as to guide the room air blown out by the air sending fan to the air outlet. The heat exchanger and the air sending fan are held by the back case which includes the integrally formed air outlet passage wall, and fixed on the installation plate which is mounted on the wall surface of the room (for example, see Patent Literature 1).